Stencil sheet



No Drawing.

This invention relates t ticularly to which the ste mit the ink through the porous support. Heretofore,

Application filed June 14, 1926.

STENCIL SHEET.

6 stencils and parstencil sheets comprising a f organic colloid, imperviou ncll characters are out to peror other colori ng to print fibers of the paper, or other which the stencils have been sisted largely objectionable of gelatine, wh mainly because paratively high price.

In order to ada making the the paper, or other In dampening coated have been hardened by alu alone, the fibers of the paper ency to stret become bagg oh so as to .cause y In the frame,

has a tendency to become stick I The main provide a coating solution for aving glue takethe place of the more 0 heretofore u objects of this in as its principal sed to provide the impervious film, with coated, conich has been of its pt the coated sheet for stencil by pressure, as for in porous supsheets which minum salts have a tendthe stencil to and the paper vention are to stencil sheets ingredient to ostly gelatine an improved hardening solution for treating the sheets after the impervi stencil sheet which after being dampened cutting of the characsheet which is and to provide an to provide a come baggy or sticky preparatory ters to pro tough and inexpensive,

to the vide a stencil improved process of making a of this kind.

Stencils may fibrous material, paper is'preferred ture.

In carryin is coated with a be made of but Japan because of g out this inventi ous film has been applied;

will not bestencil sheet any suitable ese Yoshino its thin texon, the sheet solution which preferably includes glue, glycerine, a volatile vehicle, and zinc chloride.

The glue i gives the sheet grade of hide gl face. A goo found to b cheaper than the desired inkthe principal ingredient and resisting su ue has been e satisfactory and is much the gelatine heret ofore used.

comb Serial No. 116,038.

when moistened an therefore, there has paper are toughened and tearing of the paper is greatly reduced.

e ingredients of the above solution may be combined in varied proportions, but it has been found that the best results can be obtained from a combination in the following proportions:

Parts by weight.

Glycerine ater J Zinc chloride After the sheets are coated with the above solution, they are dried by any suitable means and then coated with a hardenin solution including aluminum chloride, lyeerine, potassium dichromate and a v0 atile vehicle.

The aluminum chloride and potassium dichromate are both hardening agents and b using them combined in the hardening solution it has been found that better results are obtained than by using them separately.

- en stencil sheets are hardened with aluminum salts Without the dichromate, the fibers have a tendency to stretch after being moistened, thus causing the sheet to become' baggy in the frame. The paper also has a tendency to become sticky.v ba sheet is very obi'ectionable because of theifiiculty in proper y aligning the stencil characters during the cutting operation.

hen potassium dichromate is used alone the hardening agent, the sheet must be exposed to light, because the coagulating action of potassium dichromate on the organic c'olloid is dependent u on a light reaction which consumes consi erable time. In oraper tears very easily so that their entire sheets, upon by the light, a large der to expose the surface is acted amount of floor space is required it the stencils are to be manufactured in considerable quantities. The use of potassium dichromate alone is, therefore, objectionable.

By using the aluminum chloride and potassium dichromate in combination for the hardening solution, the sheets will not become baggy, when subsequently moistened, and the sheets need not be exposed to the light for a longer period than 1s require to evaporate the volatile solvent, usually may be combined in varied proportions,

- about one hour.

Water may be used as the carrying agent in the hardening solution. Glycerine is also used in the hardening solution in order to compensate for any glycerine in the coating solution which may have been dissolved by the water.

The ingredients in the hardening solutigmt u it has been found that the best results can be obtained from the following combination:

Parts by weight. Water 200 Aluminum chloride 5 Glycerine Potassium dichromate solution (6%) 10 The sheet may be coated on either one or both sides in any suitable manner, as by dipping, spraying or by means of a rush, rollers or the like.

Although this i vention is here particu-' 'larly described in its preferred embodiment, it will be understood that the product and the various steps of the process ma be modified by omission or alteration of etails and substitution of ingredients, without departing from the spirit of the invention as defined by the tollowing claims.

ll claim:

1. A stencil blank comprising a sheet of fibrous material coated with glue and zinc chloride.

2. A stencilblank comprising of neeause fibrous material coated with a solution including glue, glycerine and zinc chloride.

3. A stencil blank comprising a sheet of fibrous material coated with a solution in cluding an animal colloid and zinc chloride.

-4. A stencil blank comprising, a sheet of fibrous material coated with a solution including glue, glycerine, zinc chloride, and a volatile carrying agent.

5. A stencil blank comprising a sheet of fibrous material coated with a solution including an animal colloid about 22 parts, glycerine about 22 parts, about 210 parts, and zinc parts.

6. A stencil blank comprising a sheet of fibrous material coated with a solution including-glue about 22 parts, glycerine about 22 parts, water about 210 parts, and zinc chloride about 3 parts.

7. The process 0t preparing a stencil sheetwhich consists in coating the sheet with a film including glue, permitting the film to dry, and then coating the film with a hardening solution, including aluminum'chloride, glycerine, potassium dichromate and water.

8. A stencil blank comprising a sheet of fibrous material coated with glue, zinc chloride, and potassium dichromate.

9. A stencilblank comprising a sheet of fibrous material coated wi h a solution including glue, glycerine, zinc chloride and potassium chloride about 8 dichromate. 10. A stencil blank comprising a sheet of fibrous material coated with a solution including glue, glycerine, zinc chloride, po' tassium dichromate and a volatile carrying agent.

11. A stencil blank comprising a sheetof fibrous material coated with a solution including glue, glycerine, zinc chloride, potassium dichromate, aluminum chloride, and a volatile carrying agent.

Signed at C icago this 5th day of June, 1926..

cnaatns a volatile vehicle- 

